Ending up with Zombie process

["Eisenknapp, Josef" <josef eisenknapp siemens com>]

Hello again

 

The more complex my program is, the more questions i have :-)

 

My Gui should collect a bunch of values an then start a process which installs something on another computer.

To get status information to the gui during the installation process i thought about using a pipe for comunication between the gui and the installer.

 

 

 

Like described in the study guide example I open a pipe an run an example process (write_to_fff.pl).

    ------------------------------------------------------------------------

   my $fh = new IO::Pipe;
   $fh->reader("./write_to_fff.pl");

 

    my $helper_tag = Gtk2::Helper->add_watch(fileno $fh, 'in',sub{
        &watch_callback($fh)
        });

    ------------------------------------------------------------------------

 

    ----------------------------------------------------------

    # this is my write_to_fff.pl

    ------------------------------------

    #! /usr/bin/perl -w

 

    use strict;
    use warnings;

 

    my $i = 1;

 

    while($i < 10){

 

    print "Loop $i\n";
    system ("");
    $i ++;
     sleep 2;
    }
    -------------------------------------------------------------------

 

in the watch_callback() i currently just print the child process' output to STDOUT

 

    ------------------------------------------------------------------------

    sub watch_callback{

    print "callback called\n";
    my ($fh) = @_;

 

    my $line;
    $fh->sysread($line,1000);
    chomp $line;
    if($line){
          print $line. "\n";
    }
    else{
          print "remove helper\n";
          Gtk2::Helper->remove_watch($helper_tag);
    }

 

    return TRUE;
    }
    ------------------------------------------------------------------------

 

 

 

This works pretty fine, but when the process "write_to_fff.pl" terminates it becomes a ZOMBI.

 

Can anyone tell me how to avoid this?

 

I tried it like in "Programming Perl" with:

 

my $kid;
do {
    $kid = waitpid(-1, &WNOHANG);
}until $kid == -1;

 

Then the Process terminated corretly, but my watch_callback() isn't called until "write_to_fff.pl" terminates.

 

 

 

 

 

Thanks in advance

Josef